1. Field of the Invention
The present invention relates to a valve body usable in various pumps such as diaphragm pumps and piston pumps.
2. Technical Field of the Invention
There have heretofore been known valves usable in various pumps such as diaphragm pumps and piston pumps (for example, see U.S. Pat. Nos. 5,664,940, 6,158,982, 5,927,954, 5,860,794 and 5,368,452).
In general, a diaphragm pump is operated by using compressed air supplied through a valve as a drive source. As is well known, two diaphragms disposed in bilateral symmetry are provided on the opposite ends, respectively, of a center shaft reciprocatable in the axial direction, and air chambers defined inside the respective diaphragms are periodically supplied with compressed air through a valve, thereby repeating the push-pull operation of the pair of diaphragms to perform a pumping action.
FIG. 10 shows schematically a conventional pump valve usable in a double diaphragm pump. As shown in FIG. 10, the pump valve has a valve body 51 having a compressed air-filled chamber 50 formed in the center thereof, and a center shaft 52 reciprocatably extends through the compressed air-filled chamber 50 of the valve body 51. The center shaft 52 extends through air chamber blocks 53 disposed at the opposite sides of the valve body 51 to define air chambers. Diaphragms (not shown) are secured to the opposite ends, respectively, of the center shaft 52. The compressed air-filled chamber 50 of the valve body 51 is provided therein with a switching member 54 attached to the center shaft 52.
The valve body 51 is provided with a piping block 55. The piping block 55 is formed with two air supply passages 56 and 57 through which compressed air supplied into the compressed air-filled chamber 50 of the valve body 51 from a compressed air supply port (not shown) is supplied into the air chambers, respectively, and also formed with an air release passage 58 through which the compressed air supplied into the compressed air-filled chamber 50 is released into the atmosphere. A slide member 59 associated with the passages 56, 57 and 58 is disposed in the compressed air-filled chamber 50 in engagement with the switching member 54.
In the state shown in FIG. 10, the slide member 59 is in a position where it communicates the air supply passage 57 with the air release passage 58 and also communicates the air supply passage 56 with the compressed air-filled chamber 50. The compressed air in the air chamber disposed at the left-hand side as seen in the figure is discharged into the atmosphere through the air supply passage 57 and the air release passage 58. When, in this state, compressed air is supplied into the compressed air-filled chamber 50 of the valve body 51 from the compressed air supply port (not shown), the compressed air passes through the air supply passage 56 and is supplied into the air chamber disposed at the right-hand side in the figure. In response to the compressed air thus supplied, the diaphragm (not shown) disposed at the right-hand side in the figure is moved rightward, causing the center shaft 52 to move rightward. The movement of the center shaft 52 causes the slide member 59 to move rightward together with the center shaft 52, thereby allowing communication between the air supply passage 56 and the air release passage 58. As a result, the compressed air in the air chamber disposed at the right-hand side in the figure is discharged into the atmosphere through the air supply passage 56 and the air release passage 58. At the same time, the slide member 59 allows the air supply passage 57 to communicate with the compressed air-filled chamber 50. In this state, compressed air supplied into the compressed air-filled chamber 50 of the valve body 51 from the compressed air supply port (not shown) passes through the air supply passage 57 and is supplied into the air chamber disposed at the left-hand side in the figure. In response to the compressed air thus supplied, the diaphragm disposed at the left-hand side in the figure is moved leftward, causing the center shaft 52 to move leftward together with the slide member 59. This operation is repeated to perform a pumping action.
In the conventional pump valve as shown in FIG. 10, however, the air supply passages 56 and 57 are formed in the piping block 55 so that the air chamber-side ends of the air supply passages 56 and 57 align with the corresponding through-holes in the air chamber blocks 53 defining the air chambers. In other words, the through-holes of the air chamber blocks 53 have to be formed so as to align with the air chamber-side ends of the air supply passages 56 and 57, respectively. In addition, when installed, the air chamber blocks 53 have to be mounted so that their through-holes align with the air chamber-side ends of the air supply passages 56 and 57, respectively.